Add a browsertest suite for net predictor

chrome/browser/net/predictor.h

Index: chrome/browser/net/predictor.h
diff --git a/chrome/browser/net/predictor.h b/chrome/browser/net/predictor.h
index 2e6f811811e3ca1c36e414b44146f375d47ccd0b..2827ffd03ad9980a5ebeb0eae80b6f7b718b2044 100644
--- a/chrome/browser/net/predictor.h
+++ b/chrome/browser/net/predictor.h
@@ -75,7 +75,9 @@ class PredictorObserver {
   virtual void OnPreconnectUrl(const GURL& original_url,
                                const GURL& first_party_for_cookies,
                                UrlInfo::ResolutionMotivation motivation,
-                               int count) = 0;
+                               int count) {}
+  virtual void OnLearnFromNavigation(const GURL& referring_url,
+                                     const GURL& target_url) {}

[mmenke, 2016/04/22 16:29:25]

Pre-existing issue, but this file should forward declare GURL - or actually,
probably include it, since one method returns a GURL.

[Charlie Harrison, 2016/04/28 16:29:51]

Done.

 };
 
 // Predictor is constructed during Profile construction (on the UI thread),
@@ -307,6 +309,10 @@ class Predictor {
     return predictor_enabled_;
   }
 
+  // Used only for testing.

[mmenke, 2016/04/22 16:29:24]

Maybe add "Overrides command line flag to disable preconnect, which is added the
browser test fixture."

+  void set_preconnect_enabled_for_test(bool preconnect_enabled) {
+    preconnect_enabled_ = preconnect_enabled;
+  }
 
  private:
   FRIEND_TEST_ALL_PREFIXES(PredictorTest, BenefitLookupTest);
@@ -564,7 +570,7 @@ class Predictor {
   // Are we currently using preconnection, rather than just DNS resolution, for
   // subresources and omni-box search URLs.
   // This is false if and only if disabled by a command line switch.
-  const bool preconnect_enabled_;
+  bool preconnect_enabled_;
 
   // Most recent suggestion from Omnibox provided via AnticipateOmniboxUrl().
   std::string last_omnibox_host_;